The present invention relates to an electronic pan-focusing apparatus for use in a camera such as optical camera, video camera, still video camera or the like.
Various cameras having therein an automatic focusing unit for performing an automatic focusing operation have been known. When such cameras are used to make an image including an image portion of a main object as well as an image portion of a background, the automatic focusing operation is performed ordinarily to the main object, so it is difficult to make an image in which both the image portion of the main object and the image portion of the background are in focus.
In order to make an image in which any image portions are in focus in irrespective to a main object or a background, it is considered to reduce an aperture-stop of the camera lens so as to increase the depth of field, as well as to use a photographic lens having a short focal distance.
In the case that the camera having a photographic lens having a short focal distance is used to make an image for displaying or introducing, for example, relatively small goods, there occurs a problem that the image, which may include not only an image portion of an object to be photographed but also image portion of something or other around the object is taken with the camera due to an inherent wide view-angle characteristic of the lens having a short focal distance. Further, since the depth of the field is closely related to a camera exposure, it may be often restricted to increase the depth of field in order to ensure a proper camera exposure.
It is therefore an object of the invention to provide an electronic pan-focusing apparatus for a camera, which makes it possible to make an image in which any image portions can be substantially in an in-focus state independent of a depth of field or a kind of lens even when the objects have different distances with respect to the camera.
Another object of the invention is to provide an electronic pan-focusing apparatus for a camera, which can make a composite image, in which any image portions can be substantially in an in-focus state, from plural images which have been taken with the camera.
The objects of the invention can be achieved by an electronic pan-focusing apparatus for a camera having a photographic lens, comprising: image pickup means arranged to receive one or plural optical images from the lens, the image pickup means being adapted to divide each of the images into a plurality of regions in horizontal and vertical directions and to pickup image data and high-frequency component data from each of the regions; storage means for storing the image data and the high-frequency component data of each of the regions fed from the pickup means at every image; and arithmetic means adapted, when the data of the plural images are stored in the storage means, to mutually compare in magnitude the high-frequency data of the regions which take the same position in the respective images and thereby to make a composite image from the plural images by selecting one of the regions having a largest high-frequency component data in magnitude at every position, the arithmetic means being also adapted to output the image data of the regions of the composite image.
According to the present invention, in the case that data of plural images are respectively stored in the storage means, a composite image comprised of the regions selected at every position is made from the plural images. When objects having different distance with respect to the camera are taken with the camera for making an image in the image pickup means, the photographic lens of the camera is adjusted to be in focus on a part of the objects. In this case, the more the part of the objects gets closer to an in-focus state, the more a high-frequency component signal of the image region having an image data of the part of the objects increases in magnitude. Accordingly, when plural optical images of substantially the same objects having different distances with respect to the camera are made by the camera, the photographic lens of the camera is adjusted to be in focus on different parts of the objects at every image to be made. Thereafter, the composite image is made from the plural images in such a manner that one of the regions of the plural images, which has a largest high-frequency component data in magnitude, is selected at every position of region. Accordingly, it is possible to obtain the composite image in which any image portions can be substantially in an in-focus state independent of to a depth of field or a kind of lens even when the objects have different distances with respect to the camera.
Preferably, the arithmetic means is further adapted to perform interpolation of the image data at boundaries of the respective adjacent regions of the composite image. In this case, the composite image can be obtained in the state that respective adjacent portions of the image are smoothly connected to each other.
Preferably, the arithmetic means is further adapted, when data of a single image only are stored in the storage means, to pickup the image data of the regions of the image from the storage means for outputting the same. Accordingly, the single image which has been taken with the camera can be obtained as it is.
The image data may be fed from the arithmetic means to a display portion of the camera. Further, the camera may be an optical camera, a video camera, or a still video camera.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments of the present invention as illustrated in the accompanying drawings.